岛屿数量
    题目链接：https://leetcode-cn.com/problems/number-of-islands/
    图片.png

    思路：想法比较直接，遍历整个图碰到1就计数并用DFS或BFS沉掉目前这个岛屿上的所有陆地

    参考代码：

    1. class Solution {
    2. private:
    3.     int width;
    4.     int height;
    5. public:
    6.     int numIslands(vector<vector<char>>& grid) {
    7.         if (grid.size() == 0 || grid[0].size() == 0) {
    8.             return 0;
    9.         }
    10.         width = grid[0].size();
    11.         height = grid.size();
    12.         int res = 0;
    13.         for (int i = 0; i < width; ++i) {
    14.             for (int j = 0; j < height; ++j) {
    15.                 if (grid[j][i] == '1') {
    16.                     sinkIsland(grid, j, i);
    17.                     ++res;
    18.                 }
    19.             }
    20.         }
    21.         return res;
    22.     }
    24.     void sinkIsland(vector<vector<char>>& grid, int x, int y) {
    25.         if (x < 0 || x >= height || y < 0 || y >= width || grid[x][y] == '0') {
    26.             return;
    27.         }
    28.         grid[x][y] = '0';
    29.         sinkIsland(grid, x-1, y);
    30.         sinkIsland(grid, x+1, y);
    31.         sinkIsland(grid, x, y-1);
    32.         sinkIsland(grid, x, y+1);
    33.     }
    34. };